How do you make a 4,300-pound roadster accelerate to 60 miles per hour in under four seconds? Easy, just fit it with a twin-turbocharged 6.0-liter V12 that cranks out 621 horsepower and - wait for it - 738 pound-feet of torque. Sounds bonkers, right? Welcome to the 2013 Mercedes-Benz SL65 AMG.

We're all very familiar with the *63 AMG models, the majority of which are now fitted with a brand new twin-turbo 5.5-liter V8, but for those who want the ultimate in high-performance machinery (at an extremely high-dollar price), the *65 AMG cars are simply out of this world. We first feasted our eyes on the new-for-2013 SL63 AMG at the Geneva Motor Show earlier this month, but the SL will now be taking the stage at next month's New York Auto Show to debut off its range-topping spec.

The 6.0-liter V12 is hardly a new engine, though there have been a few updates including new turbochargers, manifolds and wastegate channels. The big change for 2013, however, is the pairing of Merc's seven-speed AMG Speedshift transmission. (Historically, the 65 AMG cars were mated to a five-speed auto, since it was the only transmission in the automaker's parts bin capable of handling such massive amounts of torque.)

Like the rest of the SL line, the SL65 AMG has lost a bit of weight in its overhaul - 254 pounds versus the 2012 model - mostly thanks to an all-aluminum body-on-white. The full suite of SL goodies are on tap in the 65, including the nifty Magic Sky Roof, Airscarf, speed-sensitive steering and a new sport suspension based on Merc's Active Body Control. Inside, the cabin is trimmed in only the finest of leather - including the costly Designo options - and features goodies like a Bang & Olufsen surround sound system and the latest version of Mercedes' Command infotainment software.